Composite membrane for 226Ra and 210Pb separation, its preparation method, and applications

Abstract

This invention provides a method for 226 Ra and 210 This invention relates to the field of radioactive ion extraction and separation, specifically a composite membrane for Pb separation, its preparation method, and its applications. The method includes the following steps: mixing polyacrylonitrile, crown ether, and an ionic liquid to obtain a spinning solution; spinning this solution to form a composite membrane. This invention enables the separation of Pb from uranium ore digestion solutions. 226 Ra and 210 The effective extraction and separation of Pb reduces radioactive pollution in the environment and enables the recycling of environmental resources. At the same time, the preparation method is simple and low-cost, and the resulting composite membrane is non-toxic and harmless, which is conducive to industrial application.

Description

Technical Field

[0001] This invention relates to the technical field of radioactive ion extraction and separation, and in particular to a method for... 226 Ra and 210 Composite membranes for Pb separation, their preparation methods, and applications. Background Technology

[0002] With the rapid development of the global nuclear energy industry and the expansion of uranium mining activities, the long-term infiltration of radioactive nuclides into the environment has become a global crisis. Uranium mine wastewater is enriched with radioactive nuclides... 238 U decay chain nuclide 226 Ra (half-life 1600 years) and 210 Pb (half-life 22.3 years), due to its high mobility and bioaccumulation, poses a serious threat to ecosystems and human health, such as... 226 Ra can pollute drinking water sources through groundwater, and 210 Pb accumulates in crops after atmospheric deposition, leading to a significant increase in the risk of radioactive exposure in human bone tissue.

[0003] However, these nuclides have irreplaceable scientific and engineering value: 226 The decay daughters of Ra emit broad-spectrum gamma rays (186-1764 keV), serving as a reference source for the full-band calibration of high-purity germanium detectors (HPGe). 226 Ra standard materials are also a crucial part of the work in society for monitoring radium in drinking water. 210 Pb, through sediment dating and aerosol tracing, has become a key tool for studying climate change and pollution migration. Therefore, achieving... 226 Ra and 210 The efficient extraction and separation of Pb is not only an urgent need for ecological restoration, but also a strategic prerequisite for the resource utilization of radioactive waste.

[0004] about 226 Ra and 210 Studies on the extraction and separation of phosphorus (Pb) are quite rare. Related research involves the analysis of radium isotopes during lithium extraction from geothermal brine. 210 The adsorption behavior of Pb and other radionuclides in lithium titanate oxide (LTO) particles revealed that radium isotopes and... 210 All Pb was absorbed by LTO, among which 210 Pb was almost completely adsorbed, while 226 Ra and 228 Ra adsorption rates are between 50-80%, but radium isotopes and 210Pb was simply extracted without further separation and purification. In addition, in 2020, Ma Tai applied for an invention patent for the separation of radium from lead, bismuth and thorium for medical isotope production applications. This method involves multiple processes and multiple media, making the separation process complex and cumbersome.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for 226 Ra and 210 A method for preparing Pb-separated composite membranes is presented. This method is simple, low-cost, and produces non-toxic and harmless composite membranes, which are beneficial for industrial applications.

[0007] The second objective of this invention is to provide a method for 226 Ra and 210 The composite membrane for Pb separation can achieve the separation of Pb from uranium ore digestion solution. 226 Ra and 210 Effective extraction and separation of Pb.

[0008] The third objective of this invention is to provide a method for 226 Ra and 210 The application of composite membranes for Pb separation is beneficial for reducing radioactive pollution in the environment and for the recycling of environmental resources.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] Firstly, a type of... 226 Ra and 210 The method for preparing a Pb-separated composite membrane includes the following steps:

[0011] Polyacrylonitrile, crown ether, and ionic liquid are mixed to obtain a spinning solution, which is then used to spin a film to obtain the composite film.

[0012] Furthermore, the solvent used in the mixture includes N,N-dimethylformamide.

[0013] Furthermore, the crown ether comprises DtBuCH18C6.

[0014] Furthermore, the ionic liquid includes at least one of [C6mim][NTf2], [C2mim][NTf2], and [C8mim][NTf2].

[0015] Furthermore, the ratio of polyacrylonitrile, crown ether, and ionic liquid is 13:5:10.

[0016] Furthermore, the method for spinning to form a film includes the following steps:

[0017] The spinning solution is placed in a syringe and then loaded into an electrospinning machine for spinning to form a film, thereby obtaining the composite film.

[0018] Secondly, a composite membrane prepared by any of the above-described preparation methods.

[0019] Furthermore, the composite membrane has 1-10 layers, preferably 8 layers.

[0020] Thirdly, the composite membrane described above is used for separation and extraction in the digestion solution. 226 Ra and 210 Applications in Pb.

[0021] Furthermore, the digestion solution includes a uranium ore digestion solution.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] The present invention provides for 226 Ra and 210 A method for preparing a composite membrane for uranium ore separation is simple, low-cost, and produces a non-toxic and harmless membrane, which is beneficial for industrial applications. Specifically, using crown ether as a chelating agent and an ionic liquid to provide a dynamic solvation environment, with polyacrylonitrile as a substrate, a novel electrospun membrane material is obtained through spinning, which is the desired composite membrane. This membrane can effectively separate uranium ore from its digestion solution. 226 Ra and 210 Effective extraction and separation of Pb can reduce radioactive pollution in the environment and facilitate the recycling of environmental resources.

[0024] The present invention provides for 226 Ra and 210 The composite membrane for Pb separation can achieve the separation of Pb from uranium ore digestion solution. 226 Ra and 210 Effective extraction and separation of Pb.

[0025] The present invention provides for 226 Ra and 210 The application of composite membranes for Pb separation is beneficial for reducing radioactive pollution in the environment and for the recycling of environmental resources. Attached Figure Description

[0026] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a flowchart illustrating the synthesis process of the Dt+C6@PAN membrane material provided in Embodiment 1 of the present invention.

[0028] Figure 2 The FT-IR image of the Dt+C6@PAN membrane material provided in Embodiment 1 of the present invention;

[0029] Figure 3 Thermogravimetric analysis of the Dt+C6@PAN membrane material provided in Embodiment 1 of the present invention;

[0030] Figure 4 The XRD pattern of the Dt+C6@PAN membrane material provided in Embodiment 1 of the present invention;

[0031] Figure 5 The images show scanning electron microscope (ad), particle size distribution map, and TEM-EDS image (em) of the Dt+C6@PAN membrane material provided in Example 1 of this invention before adsorbing lead and barium ions.

[0032] Figure 6 The images show scanning electron microscope (ad), particle size distribution map, and TEM-EDS image (em) of the Dt+C6@PAN membrane material provided in Example 1 of this invention after adsorbing lead and barium ions.

[0033] Figure 7 This illustrates the effect of Dt@PAN membrane materials formed from different masses of DtBuCH18C6 in Experimental Example 1 of this invention on the adsorption of lead and barium ions.

[0034] Figure 8 This is a graph showing the effect of Dt+C6@PAN membrane material on the adsorption of lead and barium ions under different nitric acid environments in Experiment Example 1 of this invention;

[0035] Figure 9 This is a graph showing the effect of the Dt+C6@PAN membrane material on the adsorption of lead and barium ions under different membrane layer numbers in Experimental Example 2 of this invention;

[0036] Figure 10 This is a graph showing the effect of the Dt+C6@PAN membrane material on the adsorption of lead and barium in the presence of competing ions in Experimental Example 2 of this invention;

[0037] Figure 11This is a graph showing the effect of Dt+C6@PAN membrane material on the adsorption of lead and barium ions at different times in Experimental Example 2 of this invention;

[0038] Figure 12 This is a graph showing the effect of Dt+C6@PAN membrane material on the adsorption of lead and barium ions at different initial concentrations in Experimental Example 2 of this invention.

[0039] Figure 13 This is a flowchart of the elution process of the Dt+C6@PAN membrane material after adsorbing lead and barium ions in Experimental Example 2 of the present invention;

[0040] Figure 14 In Experimental Example 2 of this invention, the Dt+C6@PAN membrane material was used for adsorption... 226 Ra and 210 Flowchart of Pb radionuclides elution and diagram of material recycling performance;

[0041] Figure 15 The graph shows the adsorption capacity of the composite membrane for lead and barium ions tested in Experiment 3 of this invention. Detailed Implementation

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] According to a first aspect of the invention, a method for 226 Ra and 210 The method for preparing a Pb-separated composite membrane includes the following steps:

[0044] Polyacrylonitrile, crown ether, and ionic liquid are mixed to obtain a spinning solution. This spinning solution is then used to spin a film to obtain a composite film.

[0045] The preparation method of this invention is simple and low-cost, and the resulting composite membrane is non-toxic and harmless, which is beneficial for industrial application. Specifically, using crown ether as a chelating agent, employing an ionic liquid to provide a dynamic solvation environment, and using polyacrylonitrile as a substrate, a novel electrospun membrane material is obtained through spinning, which is the desired composite membrane. This membrane can effectively treat uranium ore digestion solutions. 226 Ra and 210 Effective extraction and separation of Pb can reduce radioactive pollution in the environment and facilitate the recycling of environmental resources.

[0046] In this invention, the solvents used in the mixture include, but are not limited to, N,N-dimethylformamide; crown ethers include, but are not limited to, DtBuCH18C6, i.e., 4', 4'' (5'')-di-tert-butyldicyclohexyl-18-crown-6; and ionic liquids include, but are not limited to, at least one of [C6mim][NTf2], [C2mim][NTf2], and [C8mim][NTf2].

[0047] In a preferred embodiment, the ratio of polyacrylonitrile, crown ether, and ionic liquid can be 13:5:10, but is not limited thereto.

[0048] In a preferred embodiment, the method of spinning to form a film includes the following steps:

[0049] The obtained spinning solution was placed in a syringe and then loaded into an electrospinning machine for spinning to form a film, thus obtaining a composite film.

[0050] A type of 226 Ra and 210 A typical preparation method for Pb-separated composite membranes includes the following steps:

[0051] (a) Dissolve polyacrylonitrile (PAN) in N,N-dimethylformamide (DMF) and stir thoroughly at 50°C for 24 hours until a transparent golden yellow color is obtained to obtain a PAN solution;

[0052] (b) Add DtBuCH18C6 to the obtained PAN solution and stir thoroughly at 30°C for 48 hours until there is no white solid in the solution and the solution turns dark yellow to obtain Dt@PAN solution;

[0053] (c) Add [C6mim][NTf2] solution to the obtained Dt@PAN solution and stir thoroughly at 30°C for 12 h to obtain Dt+C6@PAN spinning solution;

[0054] (d) The obtained Dt+C6@PAN spinning solution was placed in a syringe and then loaded into an electrospinning machine for spinning to form a film (the nanofibers were received by aluminum foil) to obtain the film material.

[0055] (e) The obtained membrane material is cut using a hollow metal cylinder to obtain the finished Dt+C6@PAN membrane material, which is the desired composite membrane.

[0056] According to a second aspect of the present invention, a composite membrane prepared by any of the above-described preparation methods is provided.

[0057] The present invention provides for 226 Ra and 210 The composite membrane for Pb separation can achieve the separation of Pb from uranium ore digestion solution. 226Ra and 210 Effective extraction and separation of Pb.

[0058] In this invention, the composite membrane can have 1 to 10 layers, for example, 1, 2, 3, 4, 6, 8, or 10 layers, and is more preferably 8 layers.

[0059] According to a third aspect of the present invention, a method for separating and extracting the above-described composite membrane in a digestion solution is provided. 226 Ra and 210 Applications in Pb.

[0060] In this invention, the digestion solution includes, but is not limited to, uranium ore digestion solution.

[0061] The present invention provides for 226 Ra and 210 The application of composite membranes for Pb separation is beneficial for reducing radioactive pollution in the environment and for the recycling of environmental resources.

[0062] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0063] Example 1

[0064] A type of 226 Ra and 210 For the preparation method of the Pb separation composite membrane, see Figure 1 This includes the following steps:

[0065] (a) Weigh 65g of polyacrylonitrile (PAN) and dissolve it in 500ml of N,N-dimethylformamide (DMF). Stir thoroughly at 50℃ for 24h until a transparent golden yellow color is obtained to obtain PAN solution.

[0066] (b) Add 25g of DtBuCH18C6 to the obtained PAN solution and stir thoroughly at 30°C for 48h until there is no white solid in the solution and the solution turns dark yellow to obtain Dt@PAN solution;

[0067] (c) Add 50 ml of [C6mim][NTf2] solution to the obtained Dt@PAN solution and stir thoroughly at 30°C for 12 h to obtain Dt+C6@PAN spinning solution;

[0068] (d) The obtained Dt+C6@PAN spinning solution was placed in a 10ml syringe and then loaded into an electrospinning machine for spinning to form a film (the nanofibers were received by aluminum foil) to obtain the membrane material.

[0069] (e) The obtained membrane material is cut using a hollow metal cylinder with a diameter of 25 mm to obtain the finished Dt+C6@PAN membrane material, which is the required composite membrane.

[0070] The FT-IR image of the Dt+C6@PAN membrane material obtained in this embodiment is shown below. Figure 2 Thermogravimetric diagram can be found Figure 3 XRD pattern can be found Figure 4 .

[0071] Figure 2 Middle, 2940 cm -1 and 2860 cm -1 The peaks correspond to the asymmetric and symmetric stretching vibrations of the methyl and methylene groups, respectively; 2240 cm⁻¹ -1 The absorption peak at 1730 cm⁻¹ originates from the -C≡N nitrile group of PAN. -1 and 1451 cm -1 The peak at 1370 cm⁻¹ is related to the stretching vibrations of C=O and C=C; -1 and 1010 cm -1 The absorption peak at 569 cm⁻¹ originates from the COC bond of the crown ether; -1 The sharp peak at the point is related to the S=O oscillation of the ionic liquid, which together confirms that DtBuCH18C6 and [C6mim][NTf2] have been successfully dispersed and immobilized in the PAN matrix.

[0072] Figure 3 In the first stage (25 °C - 230 °C), the mass of Dt+C6@PAN gradually decreased, which was attributed to the evaporation of water and DMF; in the second stage, significant weight losses were observed at 301.9 °C, 361.6 °C, and 418.8 °C due to the decomposition of the crown ether ring, ionic liquid, and PAN (-C≡N) group; finally, Dt+C6@PAN lost 65.7% of its initial mass before stabilization.

[0073] Figure 4 In the PAN, a sharp peak appears at 17.1° and a broad peak appears at 26.4°, which is related to the recrystallization of PAN chains during spinning. For Dt@PAN, the main peak of DtBuCH18C6 at 18.2° is retained, but its intensity is reduced, while the small peaks at 6.8° and 9.3° disappear, indicating that the crystallinity is reduced under load. As for Dt+C6@PAN, the characteristic peaks of PAN and [C6mim][NTf2] (12.5° and 20.1°) and the characteristic peak of DtBuCH18C6 have disappeared, indicating that the addition of crown ether and ionic liquid has disrupted the order of PAN chains, and that these two components have been uniformly dispersed in the porous framework of PAN.

[0074] Figure 5 The images show the scanning electron microscope (ad), particle size distribution, and TEM-EDS (em) images of the Dt+C6@PAN membrane material before adsorption of lead and barium ions. Figure 6 The images show the scanning electron microscope (AD) image, particle size distribution map, and TEM-EDS image (EM) of the Dt+C6@PAN membrane material after adsorbing lead and barium ions.

[0075] like Figure 5 (ac) and Figure 6 As shown in (ac), the fiber morphology is clearly visible at magnifications of 200×, 500×, and 4000×, and the structure exhibits obvious uniformity. At a magnification of 500×, the diameter distribution of 200 randomly selected fibers was obtained. Figure 5 (d) and Figure 6 (d) The results showed that the fiber diameter before adsorption was mainly distributed at 1.07 ± 0.33 μm, while it decreased to 0.76 ± 0.21 μm after adsorption. This change is attributed to the hydrophilicity of Dt+C6@PAN, which plays a crucial role in the absorption of Pb. 2+ and Ba 2+ It expands initially and then contracts as water evaporates. TEM-EDS image ( Figure 5 (em) and Figure 6 (em) confirmed the uniform distribution of C, N, O, F and S in the original membrane, and showed the adsorption of Pb²⁺ and Ba. 2+ The signal proves that the ion capture was successful.

[0076] Example 2

[0077] The only difference between this embodiment and Embodiment 1 is that in step (c), [C6mim][NTf2] is replaced with [C2mim][NTf2].

[0078] The remaining steps and parameters are the same as in Example 1, and a composite membrane is obtained.

[0079] Compared with Example 1, the composite membrane obtained in this example has an adsorption capacity of 5.27 mg / g for lead ions and an adsorption capacity of 2.19 mg / g for barium ions.

[0080] Example 3

[0081] The only difference between this embodiment and Embodiment 1 is that in step (c), [C6mim][NTf2] is replaced with [C8mim][NTf2].

[0082] The remaining steps and parameters are the same as in Example 1, and a composite membrane is obtained.

[0083] Compared with Example 1, the composite membrane obtained in this example has an adsorption capacity of 7.26 mg / g for lead ions and an adsorption capacity of 2.37 mg / g for barium ions.

[0084] Experimental Example 1

[0085] Investigating the effect of different mass fractions of crown ether components on the adsorption of lead and barium ions in the material (Dt@PAN). Figure 7 In the preparation process of the material in Example 1, step (b) was specifically studied, that is, the amounts of DtBuCH18C6 added were 5g, 15g, 25g, 35g and 50g respectively, and after obtaining Dt@PAN solution, electrospinning was performed to form a film, and the process was studied in detail.

[0086] In an environment of T=298.15K, V=10ml, and 1M nitric acid, 10mg of five different membrane materials were added to a solution with lead and barium ion concentrations of 30mg / L for adsorption experiments. The adsorption capacity of each material was obtained, and the optimal ratio (wt%=5) was then determined.

[0087] The optimal mass fraction of DtBuCH18C6 was determined to be 5%, and subsequent experiments were conducted under this condition. Figure 8 The synthesized Dt+C6@PAN membrane materials were stacked (with membrane numbers of 1, 2, 3, 4, 6, 8, and 10). A solution with a lead and barium ion concentration of 30 mg / L in a 1M nitric acid environment (T=298.15K, V=10ml) was subjected to membrane permeation (T=298.15K). The ion concentration of the permeate solution was then measured to determine the optimal number of membrane layers, which was found to be 8.

[0088] Experimental Example 2

[0089] The adsorption rates of two ions were studied under different acid conditions. Figure 9 A solution with a lead and barium ion concentration of 30 mg / L at T=298.15 K, V=10 ml (in 0.1 M, 0.5 M, 1 M, 3 M, 5 M, and 8 M nitric acid environments) was subjected to a membrane (8-layer membrane) operation (T=298.15 K). The ion concentration of the membrane-treated solution was then measured to determine the optimal adsorption acidity (0.1 M nitric acid environment).

[0090] Adsorption experiments were conducted using a mixed solution, in which Pb 2+ / Ba 2+ The concentration ratios of the interfering substances were 1:0, 1:1, 1:5, 1:10, and 1:50, respectively. When each interfering substance existed alone, the adsorption efficiencies of Pb²⁺ and Ba²⁺ remained essentially unchanged (Pb...). 2+ > 95% and Ba 2+>70%), while the absorption rates of U, Bi, and Co were less than 4%, and the absorption rate of Th was no more than 10%. In the test of coexistence of all four interfering substances, Pb 2+ The adsorption efficiency remains above 95%, Ba 2+ The adsorption efficiency decreased slightly, but remained above 65%, while the adsorption rate of each interfering substance remained below 4%. These results indicate that even when the concentration of interfering substances far exceeds that of Pb... 2+ and Ba 2+ Even at low concentrations, Dt+C6@PAN maintains excellent selectivity for the target ion, highlighting its effectiveness in separating mineral digests containing a large number of competing species. 226 Ra and 210 The great potential of Pb.

[0091] The effect of competitive ion coexistence on the adsorption of lead and barium ions by the material ( Figure 10 (a): A mixed solution with lead and barium ion concentrations of 1 mg / L and uranium concentrations of 0, 1 mg / L, 5 mg / L, 10 mg / L, and 50 mg / L, respectively, was subjected to a membrane pass-through operation at V=10 ml and T=298.15 K. The ion concentrations of the solution after membrane pass-through were then measured to obtain the adsorption rates for the three ions. (bd) The operation procedure is the same as that in a, with the corresponding ions being thorium, cobalt, and bismuth, respectively. (e): With lead and barium ion concentrations of 1 mg / L and the simultaneous presence of uranium, thorium, cobalt, and bismuth ions (at which point the concentrations of the four ions are the same, and the ratios of uranium, thorium, cobalt, and bismuth to lead / barium ions are 1:1, 5:1, 10:1, and 50:1, respectively), a membrane pass-through operation was performed at V=10 ml and T=298.15 K. The ion concentrations of the solution after membrane pass-through were then measured to obtain the adsorption rates for the six ions.

[0092] The adsorption kinetics were analyzed using pseudo-first-order and pseudo-second-order models. Fitting results show that the pseudo-second-order model better describes the adsorption of Pb. 2+ and Ba 2+ Adsorption behavior of Pb ions 2+ : Nonlinear R 2 = 0.970, linear R 2 = 0.999; Ba 2+ : Nonlinear R 2 = 0.982, linear R 2 = 0.999), indicating that chemisorption is the main mechanism of this process.

[0093] dynamics( Figure 11(a): V=10ml, T=298.15K, lead ion concentration of 30mg / L, 80mg Dt+C6@PAN material was added, and sampling points were taken at time intervals of 1, 3, 5, 10, 15, 20, 30, 40, 60, 80, 120, 180, 300, and 540min. The ion concentrations were measured, and the data were further fitted to the kinetic model (second-order kinetics); (a): V=10ml, T=298.15K, barium ion concentration of 30mg / L, 80mg Dt+C6@PAN material was added, and sampling points were taken at time intervals of 1, 3, 5, 10, 15, 20, 30, 40, 60, 80, 120, 180, 300, and 540min. The ion concentrations were measured, and the data were further fitted to the kinetic model (second-order kinetics).

[0094] The adsorption data were fitted to Langmuir and Freundlich models. The Langmuir model showed a higher correlation coefficient (Pb). 2+ : Nonlinear R 2 = 0.993, linear R 2 = 0.990; Ba 2+ : Nonlinear R 2 = 0.990, linear R 2 =0.991) and has a low chi-square value (Pb 2+ : χ 2 = 0.483; Ba 2+ : χ 2 = 0.081), indicating better fitting performance. The maximum adsorption capacity (Q) calculated according to the Langmuir model max The following are Pb: 2+ 26.045 mg / g; Ba 2+ The concentration was 11.926 mg / g. These findings confirm that the Langmuir model is more suitable for these two ions, which means that the adsorption sites on Dt+C6@PAN are evenly distributed, which is conducive to monolayer adsorption.

[0095] Isothermal adsorption line ( Figure 12(a): V=10ml, T=298.15K, initial concentrations of lead ion solutions were 10, 20, 30, 40, 50, 60, 80, 100, and 150 mg / L, respectively. Adsorption experiments were conducted at t=6h. Lead ion concentrations were measured in the solutions after complete adsorption, and the data were further fitted to an isotherm model (chemisorption). (b): V=10ml, T=298.15K, initial concentrations of barium ion solutions were 10, 20, 30, 40, 50, 60, 80, 100, 150, and 180 mg / L, respectively. Adsorption experiments were conducted at t=6h. Barium ion concentrations were measured in the solutions after complete adsorption, and the data were further fitted to an isotherm model (chemisorption).

[0096] Simulated feed elution experiment ( Figure 13 The membrane separation system consists of a flexible tube, a peristaltic pump, and a custom-designed membrane column. Eight membrane layers are stacked inside the column and activated with 10 ml of 0.1 M nitric acid. Then, a stock solution (with lead ion concentration of 10 μg / L and barium ion concentration of 800 μg / L - 2 ml) is added. The feed rate is adjusted by the pump speed and maintained at 0.4 mL / min. Barium and lead ions are eluted with 1 M HNO3 and 0.25 M Na2H2EDTA·2H2O, respectively. 2 ml of eluent is collected in centrifuge tubes, and Pb is determined by ICP-MS. 2 + and Ba 2 + The concentrations of each component were determined, and separation curves were plotted. Experimental results showed that Ba... 2+ Concentrated in 48 mL of solution (impurity Pb) 2+ The content is 0.26 wt%, while Pb 2+ It was concentrated in another 6 mL solution (impurity Ba) 2+ The content is 0.39wt%.

[0097] Real liquid elution experiment and material recycling experiment ( Figure 14 The membrane separation system consists of flexible tubing, a peristaltic pump, and a custom-designed membrane column; 32 membrane layers are stacked inside the column and activated with 10 ml of 0.1 M nitric acid, followed by the addition of 2 ml of uranium ore digestion solution (wherein, 226 The total Ra activity was 57.40 Bq. 210 The total Pb activity was 15.82 Bq. The injection rate was adjusted by the pump speed to maintain 0.4 mL / min, and the sample was rinsed with 1 M HNO3 and 0.25 M Na2H2EDTA·2H2O, respectively. 226 Ra and 210 Pb was collected in centrifuge tubes at 2 ml eluent concentrations. Within a certain time period, the total γ-decay count of the corresponding nuclide in each centrifuge tube was measured using a well-type high-purity germanium analyzer to determine the recovery rate. Repeatability test: The above experiment was repeated four times, and a reuse graph was plotted sequentially.

[0098] 226 Ra was concentrated in 84 mL of solution ( 210 Pb activity accounted for 4.11%. 210 Pb was concentrated in another 20 mL of solution ( 226 Ra activity accounted for 1.26%); 210 The regeneration rate of Pb on Dt+C6@PAN was close to 100%, and the adsorption-desorption performance did not change significantly. In contrast, 226 The adsorption efficiency of Ra decreased slightly from 70.7% to 62.6%, while its desorption efficiency remained around 100%. These results indicate that Dt+C6@PAN exhibits good reusability under practical feeding conditions and is a promising recyclable adsorbent for the separation of radionuclides.

[0099] Experimental Example 3

[0100] The adsorption capacities of the composite membranes obtained in Examples 1-3 for lead and barium ions are shown in the figures. Figure 15 The horizontal axis represents the different types of ionic liquids used, from left to right: [C2mim][NTf2], [C6mim][NTf2], and [C8mim][NTf2]. The vertical axis shows that the adsorption capacity of the composite membrane for lead and barium ions increases after adding each different ionic liquid, with the [C6mim][NTf2] ionic liquid showing the most significant improvement.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for 226 Ra and 210 The method for preparing a composite membrane for Pb separation is characterized by, Includes the following steps: (a) Weigh 65g of polyacrylonitrile and dissolve it in 500ml of N,N-dimethylformamide. Stir thoroughly at 50℃ for 24h until a transparent golden yellow color is obtained to obtain PAN solution. (b) Add 25g of DtBuCH18C6 to the obtained PAN solution and stir thoroughly at 30°C for 48h until there is no white solid in the solution and the solution turns dark yellow to obtain Dt@PAN solution; (c) Add 50 ml of [C6mim][NTf2] solution to the obtained Dt@PAN solution and stir thoroughly at 30°C for 12 h to obtain Dt+C6@PAN spinning solution; (d) The obtained Dt+C6@PAN spinning solution was placed in a 10ml syringe and then loaded into an electrospinning machine for spinning to form a film, thus obtaining the membrane material; (e) The obtained membrane material is cut using a hollow metal cylinder with a diameter of 25 mm to obtain the finished Dt+C6@PAN membrane material, thus obtaining the composite membrane.

2. A composite membrane prepared by the preparation method according to claim 1.

3. The composite membrane according to claim 2, characterized in that, The composite membrane has 1-10 layers.

4. The composite membrane according to claim 3, characterized in that, The composite membrane has 8 layers.

5. The composite membrane according to any one of claims 2-4 for separation and extraction in digestion solution. 226 Ra and 210 Applications in Pb.

6. The application according to claim 5, characterized in that, The digestion solution includes uranium ore digestion solution.

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